Payment added arrears due to system not processing payment

They were supposed to debit money on my account I tried making payment the system was down then they decided to add penalty or arrears money but the problem was with their system tried emailing them till this day no response I learn that my account was handed over now I’m blacklisted due to their system glitch I’m only gonna pay the amount I was owing them until they sort the matter out they not gonna **** us our hard earned money